1. Field of the Invention
The present invention relates to a method for truing a grinding wheel, that is, reshaping the grinding wheel or compensating for asymmetric wear of the grinding wheel, and a device used to perform such a method.
2. Description of the Prior Art
A so-called "super grinding wheel," which contains diamond particles, CBN (cubic boron nitride) particles or similar particles as the abrasive grain, is well known in the grinding industry. In recent years, workpieces have become more difficult to grind, because various types of abrasion resistive materials have become widely used in many industries. In addition, there are strong demands to increase the dimensional precision and the grinding efficiency of the workpieces. As a result, the use of such a super grinding wheel has rapidly grown.
Conventional methods for truing the super grinding wheel may involve (1) utilizing a diamond tool, such as a single diamond dresser, a diamond impregnated dresser and a block dresser, (2) utilizing a block-like grindstone or a rotary grindstone made of GC (SiC), WA (AL.sub.2 O.sub.3) and similar materials, and (3) utilizing a tool made of mild steel (which will be referred to as a "mild steel grinding method").
However, method (1) requires a lengthy dressing operation to restore the grinding power of the grinding wheel that must be performed after the truing operation is completed, because the abrasive grain particles protruding from the treatment surface of grinding wheel are worn during the truing operation, such that the tip of each abrasive grain particle is substantially flattened. This may lower the efficiency of the truing operation and decrease the precision of the trued grinding wheel. In addition, this method may cause the truing tool to wear rapidly, thus resulting in increased truing costs.
Further, each of methods (2) and (3) does not provide sufficient truing power. Therefore, it may take a long time to true the grinding wheel.
Moreover, conventional methods for truing the super grinding wheel also involve (4) utilizing a brake truer, such as a rotary dresser, a diamond wheel and other rotary tools, (5) a lapping method utilizing uncombined or free abrasive particles, (6) a crush roller method in which a rotating cylindrical metal is pressed against the grinding wheel to be treated, and (7) an electrical or non-contact method utilizing an electrical discharge.
Each of methods (4) to (7), when applied to the super grinding wheel, also does not provide satisfactory truing capability. Also, each of these methods has a limited range of application. Thus, such methods are not suitable for application to various types of grinding machines (including double-disk grinding machines or special purpose grinding machines). Further, such methods cannot be applied to various types of super grinding wheels in which the abrasive grain particles are combined using different types of binding agents.